Polyolefins such as high density polyethylene (HDPE) homopolymer and linear low density polyethylene (LLDPE) copolymer can be produced using various combinations of catalyst systems and polymerization processes. In some end-use applications, it can be beneficial to use a catalyst system having both a Ziegler-type catalyst component and a metallocene catalyst component to produce polymers having high molecular weights and broad molecular weight distributions. Accordingly, it is to these ends that the present invention is directed.